Abstract

Introduction: The purpose of this study was to evaluate the effect of different doses of retinoic acid on resumption of meiosis, in vitro maturation of oocytes and resulting embryo development in mice. Materials and Methods: Germinal vesicle of NMRI female mouse (6-8 weeks old) oocytes were collected from ovaries and cultured in maturation medium MEM-α contained: 100 mlIU/ml rFSH + 7.5 IU/ml hCG + 5 FCS (Control group). All-trans retinoic acid (t-RA) at concentrations of 0.25, 0.5, 1, 2μM and ethanol alone (Sham group) 0.2 (v/v), were added to oocytes maturation medium. After 24 hours the matured oocytes were inseminated with spermatozoa in T6 medium and cultured for 5 days. Results: The difference between our experimental and control groups in resumption of meiosis increased by t-RA dose from 0.25μM (p<0.01) to 0.5μM (p<0.001), 1μM (p<0.001) and 2μM (p<0.0001), but higher doses like 5μM and 10μM reduced it. The rate of oocytes developing to the Metaphase II stage of maturation was significantly increased with t-RA doses of 1μM (p<0.01) and 2μM (p<0.0001). The rate of embryos reaching to 2-cell after 24 hours was significantly increased with 1 (p<0.05) and 2μM t-RA (p<0.01). The rate of embryo developing to blastocyst stage was significantly increased in medium containing 2μM retinoic acid (p<0.01). Conclusion: All- trance retinoic acid enhanced mouse oocytes maturation in vitro and improved embryo development in a dose dependent manner.